Constructal law explains the sense of evolution (morphing to improve flows) of beings, but paradoxes do exist as not all vegetables have a tree form. Also, not all animals are optimized for displacement. This work aims at identification of the design functions or objectives that guide evolution under the overall statement of constructal law. This work adopted the system engineering technique of segregation between functions (abstract objectives) and solutions (physical entities). Further, this work introduced the assumptions of flow under external threats and pipes subject to leakages. Results showed that there are always elements doing four functions in pipe element: to reduce flow entropy, to protect flow channel, to retain flow content and to increase flow drive. Although the four functions are always present, natural systems typically privileges some functions over others, depending on environmental pressures. As a solution to improve flows, animal brains also fit in the model of four functions. Human mind seems to have groups of instincts associated to each of the four pipe design functions (fear, attachment, curiosity and greed). Finally, the four functions model unified physics and animal psychology.